Low molecular weight structured polymer dispersants

ABSTRACT

The present invention relates to novel low molecular weight, structured polymer compositions. The invention also relates to methods for inhibiting scale formation, precipitation or deposition; increasing dispersion of insoluble precipitates in process waters; treating cooling and boiler water; and reducing the viscosity of mineral slurries using the aforementioned polymer compositions.

This is a continuation of application Ser. No. 08/577,524, filed Dec. 22, 1995, now abandoned entitled LOW MOLECULAR WEIGHT STRUCTURED POLYMERS.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to novel low molecular weight, structured polymer compositions. The invention also relates to methods for inhibiting scale formation, precipitation or deposition; increasing dispersion of insoluble precipitates in process waters; treating cooling and boiler water; and reducing the viscosity of mineral slurries using the aforementioned polymer compositions.

BACKGROUND OF THE INVENTION

Industrial and residential waters contain naturally occurring contaminates (i.e., calcium, iron, barium, bicarbonate, carbonate, oxide, oxylate, sulfate, phosphate, zinc, etc.) that under conditions of use can chemically combine to form water insoluble precipitates. Additionally, water insoluble contaminates such as clay, silica and iron oxides can settle out of the water. These precipitates and inert materials can collect on surfaces of containers and piping in the form of deposits and scales which reduce heat transfer, inhibit flow, increase likelihood of corrosion and enhance bacterial growth. In mining applications, compositions which aid in fluidizing insoluble particulates are desirable in order to more efficiently procure and transport the mined materials.

Current mechanisms for controlling scale and deposits involve preventing formation of insoluble precipitates (e.g., limiting crystal growth) or keeping inert insoluble materials dispersed in the system. Dispersants fluidize precipitates, silts, solids and combinations thereof. Chelants or sequestering agents can be used to bind cations to help prevent the formation of insoluble precipitates. Surface active agents can be used to aid in the dispersion of inert clays and silica. By nature, some of these agents may also be useful in fluidizing high solids slurries of ores and minerals.

Certain low molecular weight organic polymers (less than 100,000 MW) are capable of both inhibiting precipitation and keeping insoluble contaminates dispersed. These polymers are comprised of polycarboxylic and polysulfonic acids and their salts, copolymers of these acids, and co- and interpolymers of these acids with acrylamide, cationic monomers, vinyl esters and ethers.

In U.S. Pat. No. 3,463,730, Booth and Mead describe a process for controlling or preventing scale deposits in aqueous systems by addition of a low molecular weight (1,000-8,000) unhydrolyzed polyacrylamide. Booth and Cornelius, in U.S. Pat. No. 3,709,815 disclose polymers containing 2-acrylamido-2-substituted propane-1-sulfonic acid with an average molecular weight of at least 20,000 for use as boiler water dispersives and conditioners. In U.S. Pat. No. 3,898,037, Lange et al., describe polymers and co-polymers of acrylamido-sulfonic acid used in dispersing water-insoluble compounds of iron, calcium, magnesium, aluminum and commonly occurring particles of silt and clay. Amick et al., in U.S. Pat. No. 4,711,725, disclose a variety of copolymers, terpolymers and interpolymers also utilzed for these applications. In each patent, the polymers described are linear in structure and completely water-soluble.

Low molecular weight organic polymers that are linear and water soluble have also been disclosed to fluidize or disperse minerals in high concentration slurries. This allows more economical storage and transport forms of the minerals. Amick et al., in U.S. Pat. No. 4,711,725 demonstrates the abilities of co- and terpolymers of carboxylic and sulfonic acids to reduce the viscosity of clay and calcium carbonate slurries. Again, these polymer compositions have a linear structure and are water soluble.

Structured, high molecular weight polymers have been previously disclosed. Ryles et al., in U.S. Pat. No. 5,171,808, disclose cross-linked, anionic or amphoteric, organic, polymeric microparticles for use in flocculating dispersions of suspended solids. In European Patent Application 0 374 458, Neff et al. disclose water-soluble, branched polymeric flocculants based on polymerization of ethlyenically unsaturated monomers and branching agents in the presence of a chain-transfer agent. Both of these patents disclose compositions of high molecular weight polymers used as flocculating agents, and used to induce massing and precipitation of insoluble materials rather than dispersion of insoluble materials in a multiphase system.

While the aforementioned compositions utilized as scale inhibitors and dispersants may be applicable under specific conditions, they are only moderately effective or ineffective under certain circumstances. Therefore, a need exists for alternative compositions and methods for inhibiting scale formation, precipitation or deposition; increasing dispersion of insoluble precipitates in process waters; treating cooling and boiling water; and reducing the viscosity of mineral slurries.

SUMMARY OF THE INVENTION

This invention provides novel low molecular weight structured polymer compositions comprising ethylenically unsaturated monomers and structure-inducing agents. These structured polymers possess molecular structure that is branched, cross-linked or some combination thereof, as opposed to polymers that possess linear molecular structure. The structured polymers of this invention have improved capability for inhibiting the formation, precipitation or deposition of scale, improved capability of dispersing insoluble precipitates in aqueous systems, improved capability in treating cooling and boiler water, and improved capability to reduce the viscosity of mineral slurries compared to existing polymers.

It is a principal object of this invention to provide polymer compositions having a molecular weight of less than about 500,000 comprising at least one unsaturated organic monomer or salts thereof, and at least one structure-inducing agent.

Other objects of this invention are to provide: methods for inhibiting scale formation, precipitation or deposition in an aqueous medium comprising the step of adding to said aqueous medium an effective amount of a polymer composition comprising at least one unsaturated organic monomer and at least one structure-inducing agent; methods for increasing dispersion of insoluble precipitates in process waters comprising the step of adding to said process waters an effective amount of a polymer composition comprising at least one unsaturated organic monomer and at least one structure-inducing agent; methods of treating cooling and boiler water comprising the step of adding to said cooling and boiler water an effective amount of a polymer composition comprising at least one unsaturated organic monomer and at least one structure-inducing agent; and methods of reducing the viscosity of a mineral slurry comprising the step of adding to said slurry an effective amount of the polymer composition comprising at least one unsaturated organic monomer and at least one structure-inducing agent.

DETAILED DESCRIPTION OF THE INVENTION

In order that the invention herein described may be more fully understood, the following detailed description is set forth. In the description, the following abbreviations are used:

    ______________________________________                                         Designation  Reagent or Fragment                                               ______________________________________                                         AA           acrylic acid                                                        AM acrylamide                                                                  AMPS 2-acrylamido-2-methylpropane sulfonic                                      acid                                                                          COM. commercial                                                                DADMAC diallyldimethylammonium chloride                                        EDTA ethylenediaminetetraacetic acid                                           GPC gel permeation chromatography                                              MA methyl acrylate                                                             MAn maleic anhydride                                                           MBA methylenebisacrylamide                                                     MBS sodium metabisulfite                                                       ME 2-mercaptoethanol                                                           NVP N-vinylpyrrolidone                                                         PAA polyacrylic acid                                                           SAHS sodium allyloxy-2-hydroxypropylsulfonate                                  T-BAM t-butylacrylamide                                                      ______________________________________                                    

The following terms are employed herein:

The term "branching" refers to the creation of branches or additional termini relative to the two original termini that exist in linear entities.

The term "branching agent" refers to an agent which causes branching to occur.

The term "cross-link" refers to an interconnection between polymer chains.

The term "cross-linking agent" refers to an agent which induces cross-linking, branching or a combination thereof to occur.

The term "ethylenically unsaturated" refers to the presence of at least one unsaturated ethylenic group.

The term "interpolymer" refers to a polymer formed from three or more different monomers.

The term "monomer" refers to single, discreet molecule which is capable of combining to form polymers.

The term "structured polymer" refers to a polymer prepared with incorporation of a structure-inducing agent.

The term "structure-inducing agent" refers to an agent which, when added to a polymer composition, induces branching, cross-linking or a combination thereof.

In view of the above definitions, other terms of chemical and polymer technology used throughout this application can be easily understood by those of skill in the art. Terms may be used alone or in any combination thereof.

This invention provides a polymer composition having a molecular weight of less than about 500,000 comprising at least one unsaturated organic monomer or salts thereof, and at least one structure-inducing agent.

In a preferred embodiment of this invention, each unsaturated organic monomer is independently selected from the group consisting of monoethylenically unsaturated carboxylic acids, monoethylenically unsaturated carboxylic acid anhydrides, monoethylenically unsaturated sulfonic acids, and sulfonated styrene. More preferably, each unsaturated organic monomer is independently selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, maleic anhydride, 2-acrylamido-2-methylpropane sulfonic acid, 2-methacrylamido-2-methylpropane sulfonic acid, and allyloxy-2-hydroxypropyl sulfonic acid.

In another preferred embodiment of this invention, the structure-inducing agent is a crosslinking or branching agent. More preferably, the structure-inducing agent is independently selected from the group consisting of polyunsaturated acrylic amides, polyunsaturated acrylic esters, alkenyl-substituted heterocycles, tri- or tetra-allylic quaternary ammonium halides, and aldehydes. Even more preferably, the structure-inducing agent is independently selected from the group consisting of methylenebisacrylamide, triallylmethylammonium chloride, ethylene glycol diacrylate, glyoxal and formaldehyde.

In a further embodiment, this invention provides a polymer composition having a molecular weight of less than about 500,000 comprising a copolymer of unsaturated organic monomers and a structure-inducing agent.

In a preferred embodiment of this invention, the copolymer comprises unsaturated organic monomers independently selected from the group consisting of monoethylenically unsaturated carboxylic acids, monoethylenically unsaturated carboxylic acid anhydrides, monoethylenically unsaturated sulfonic acids and sulfonated styrene. More preferably, the copolymer comprises unsaturated organic monomers independently selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, maleic anhydride, 2-acrylamido-2-methylpropane sulfonic acid, 2-methacrylamido-2-methylpropane sulfonic acid and allyloxy-2-hydroxypropyl sulfonic acid.

In another embodiment, the copolymer comprises one unsaturated organic monomer independently selected from the group consisting of monoethylenically unsaturated carboxylic acids, monoethylenically unsaturated carboxylic acid anhydrides, monoethylenically unsaturated sulfonic acids and sulfonated styrene; and one unsaturated organic monomer selected from the group consisting of unsaturated acrylic amides, unsaturated acrylic esters, alkenyl-substituted heterocycles and unsaturated quaternary ammonium halides. More preferably, the copolymer comprises an unsaturated organic monomer selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, maleic anhydride, 2-acrylamido-2-methylpropane sulfonic acid, 2-methacrylamido-2-methylpropane sulfonic acid, allyloxy-2-hydroxypropyl sulfonic acid and sulfonated styrene; and an unsaturated organic monomer selected from the group consisting of acrylamide, substituted acrylamides, N-vinylpyrrolidone, methacrylate, ethylacrylate, and diallylic quaternary ammonium halides.

In another embodiment, this invention provides a polymer composition having a molecular weight of less than about 500,000 comprising an interpolymer of unsaturated organic monomers and a structure-inducing agent.

In a preferred embodiment, the interpolymer comprises at least one unsaturated organic monomer independently selected from the group consisting of monoethylenically unsaturated carboxylic acids, monoethylenically unsaturated carboxylic acid anhydrides, monoethylenically unsaturated sulfonic acids and sulfonated styrene; and additional unsaturated organic monomers independently selected from the group consisting of monoethylenically unsaturated carboxylic acids, monoethylenically unsaturated carboxylic acid anhydrides, monoethylenically unsaturated sulfonic acids, sulfonated styrene, unsaturated acrylic amides, unsaturated acrylic esters, alkenyl-substituted heterocycles and unsaturated quaternary ammonium halides.

More preferably, at least one unsaturated organic monomer is independently selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, maleic anhydride, 2-acrylamido-2-methylpropane sulfonic acid, 2-methacrylamido-2-methylpropane sulfonic acid, allyloxy-2-hydroxypropyl sulfonic acid and sulfonated styrene; and additional unsaturated organic monomers are independently selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, maleic anhydride, 2-acrylamido-2-methylpropane sulfonic acid, 2-methacrylamido-2-methylpropane sulfonic acid, allyloxy-2-hydroxypropyl sulfonic acid, acrylamide, substituted acrylamides, N-vinylpyrrolidone, methacrylate, ethylacrylate, and diallylic quaternary ammonium halides.

In an alternate embodiment, this invention provides a polymer composition having a molecular weight of less than about 500,000 comprising at least one unsaturated organic monomer or salts thereof, and at least one structure-inducing agent, wherein unsaturated organic monomers independently selected from the group consisting of monoethylenically unsaturated carboxylic acids, monoethylenically unsaturated carboxylic acid anhydrides, monoethylenically unsaturated sulfonic acids and sulfonated styrene comprise between about 50% and about 100% of the total composition and more preferably between about 70% and about 100% of the total composition.

In a further embodiment, this invention provides a polymer composition having a molecular weight of less than about 500,000 comprising at least one unsaturated organic monomer or salts thereof, and at least one structure-inducing agent, wherein the molecular weight of the polymer is less than 100,000 amu, and more preferably less than 50,000 amu.

In another embodiment, this invention provides a polymer composition having a molecular weight of less than about 500,000 comprising at least one unsaturated organic monomer or salts thereof, and at least one structure-inducing agent, wherein the concentration of structure-inducing agent is between about 50 and about 20,000 ppm.

In an alternate embodiment, this invention provides methods for inhibiting scale formation, precipitation or deposition in an aqueous medium; for increasing dispersion of insoluble precipitates in process waters; and for treating cooling and boiler water; comprising the step of adding to said aqueous medium, process waters and cooling and boiler water an effective amount of a polymer composition having a molecular weight of less than about 500,000 comprising at least one unsaturated organic monomer and at least one structure-inducing agent.

In another embodiment, this invention provides a method of reducing the viscosity of a mineral slurry comprising the step of adding to said slurry an effective amount of the polymer composition having a molecular weight of less than about 500,000 comprising at least one unsaturated organic monomer and at least one structure-inducing agent. In a preferred embodiment, the mineral slurry comprises one or more minerals selected from the group consisting of calcium carbonate, titanium dioxide, coal, calcined kaolin clay and hydrated kaolin clay. In an alternate preferred embodiment the mineral slurry comprises at least one metal, preferably a transition metal.

In alternate preferred embodiments, this invention includes the methods described above wherein the polymer composition comprises the preferred, more preferred and even more preferred polymer compositions described above.

The structured polymers described herein can be prepared by conventional polymerization techniques well-known to those skilled in the art. Such techniques include, but are not limited to, solution polymerization, reverse-phase emulsion polymerization and suspension polymerization. Polymerization may be initiated via a free radical initiator. The preferred initiator method is free radical, however, photochemical or radiation methods may also be utilized. The introduction of the structure-inducing agent may be performed either prior to, concurrent with or after combining the other agents necessary for formation of the structured polymers of this invention.

Where carboxylic acids, or their salts thereof, are used for the preparation of compositions of this invention, it is also envisioned that esters, amides or nitrites may be hydrolyzed to give the desired carboxylic acid. This hydrolysis may occur before or after a polymerization event.

In order to obtain the low molecular weight polymers of this invention, it is necessary to use a chain transfer agent in their preparation. Examples of chain transfer agents which may be used are well-known to those skilled in the art. They include, but are not limited to, agents such as alcohols, phosphates, phosphinic acids, sulfites, mercaptans, and thioacids. The amount of chain transfer agent necessary will be influenced by factors such as efficiency of the compound, the monomer mixture used, the amount of structure-inducing agent present and the desired molecular weight of the final product. A combination of two or more chain transfer agents may be used in one formulation.

In order that this invention be more fully understood, the following examples are set forth. These examples are for the purposes of illustration and are not to be construed as limiting the scope of the invention in any way.

EXAMPLES Example 1

Copolymers containing 40 weight % AMPS/60 weight % AA and 20 weight % AMPS/80 weight % AA, neutralized to pH 3.5-6.0 with sodium hydroxide, were prepared via aqueous solution polymerization. Ammonium persulfate and sodium metabisulfite were used as the initiator/chain transfer system. The formulations contained 0-5000 ppm MBA as the structure inducing agent. The final products were between 30% and 40% active as acid. Specific data, including molecular weight as determined by GPC, are detailed in Table 1.

                  TABLE 1                                                          ______________________________________                                         SAMPLE   COMPOSITION    PPM MBA   MW                                           ______________________________________                                         1A       40/60 AMPS/AA  0         25,900                                         1B 40/60 AMPS/AA 100 18,100                                                    1C 20/80 AMPS/AA 0 14,100                                                      1D 20/80 AMPS/AA 5000 87,100                                                   1E 20/80 AMPS/AA 0 19,300                                                      1F 20/80 AMPS/AA 1000 18,200                                                   1G 20/80 AMPS/AA 0 7,400                                                       1H 20/80 AMPS/AA 1000 4,940                                                    1I 20/80 AMPS/AA 5000 6,400                                                  ______________________________________                                    

Example 2

Homopolymers of polyacrylic acid were prepared by the same method described in Example 1 without neutralization. Polymer formulations contained from 0-20,000 ppm MBA as the structure inducing agent. In some cases 2-mercaptoethanol (ME) was used in conjunction with sodium metabisulfite (MBS) as the chain transfer system. Specific data are given in Table 2.

                  TABLE 2                                                          ______________________________________                                                                          MOLECULAR                                       SAMPLE CHAIN TRANSFER PPM MBA WEIGHT                                         ______________________________________                                         2A      MBS           500                                                        2B MBS 1,000 57,000                                                            2C MBS 1,000 65,600                                                            2D MBS/2ME 1,250  7,400                                                        2E MBS/2ME 2,500  8,800                                                        2F MBS/2ME 5,000 11,000                                                        2G MBS/2ME 5,000 --                                                            2H MBS/2ME 10,000 --                                                           2I MBS/2ME 15,000 --                                                           2J MBS/2ME 20,000 --                                                           2K MBS/2ME 15,000 --                                                           2L MBS/2ME 5,000 --                                                            2M MBS/2ME 5,000 --                                                          ______________________________________                                    

Example 3

A series of homo-, co- and terpolymers were prepared with other carboxylic acids, sulfonic acids and several co- and terpolymers were prepared incorporating cationic and nonionic molecules in the polymer composition. All polymers were prepared according to Example 1 and adding 0 to 5000 ppm MBA as the structure inducing agent. Specific data are given in Table 3. All polymers shown in Table 3 were prepared to achieve a desired molecular weight below 15,000.

                  TABLE 3                                                          ______________________________________                                         SAMPLE    COMPOSITION       PPM MBA                                            ______________________________________                                         3A        60/20/20 AA/AMPS/DADMAC                                                                          0                                                    3B 60/20/20 AA/AMPS/DADMAC 5000                                                3C 70/20/10 AA/AMPS/NVP 0                                                      3D 70/20/10 AA/AMPS/NVP 5000                                                   3E 80/20 AA/SAHS 0                                                             3F 80/20 AA/SAHS 5000                                                          3G 70/20/10 AA/AMPS/AM 0                                                       3H 70/20/10 AA/AMPS/AM 5000                                                    3I 80/20 AA/AM 0                                                               3J 80/20 AA/AM 5000                                                            3K 70/20/10 AA/AMPS/MA 0                                                       3L 70/20/10 AA/AMPS/MA 5000                                                    3M 80/20 AA/MA 0                                                               3N 80/20 AA/MA 5000                                                            3O HOMOPOLYMER AMPS 0                                                          3P HOMOPOLYMER AMPS 5000                                                       3Q 70/20/10 AA/AMPS/TBAM 0                                                     3R 70/20/10 AA/AMPS/TBAM 5000                                                  3S HOMOPOLYMER MAn 0                                                           3T HOMOPOLYMER MAn 5000                                                      ______________________________________                                    

Examples 4-13

All of the samples described in Examples 1-3 were tested for performance in a variety of applications. The samples described in Examples 1-3 also were tested against commercially available materials that are presently used for these applications. Molecular weights were measured on the commercial products by GPC using the same method as was used for the laboratory samples described in the examples. As different methods of analysis can produce a variation in the result, molecular weights on all materials were measured by the same procedure. Data on these commercial products is detailed in Table 4.

                  TABLE 4                                                          ______________________________________                                         SAMPLE      COMPOSITION     MW                                                 ______________________________________                                         4A          COM. AA/AMPS    28,700                                               4B COM. AA/AMPS 8,100                                                          4C COM. PAA 3,730                                                              4D POLYACRYLATE (COM) 5,400                                                    4E POLYACRYLATE (COM) 3,900                                                    4F POLYACRYLATE (COM) 4,500                                                  ______________________________________                                    

Example 4 Calcium Carbonate Inhibition

    __________________________________________________________________________     SET 1 - 70° C., 1 PPM POLYMER DOSAGE                                    SAMPLE                                                                              POLYMER       PPM MBA                                                                              MW      % INHIBITION                                  __________________________________________________________________________       1A 60/40 AA/AMPS 0 25,900 36.7                                                 1B 60/40 AA/AMPS 100 18,100 42.2                                               1C 80/20 AA/AMPS 0 14,100 40.4                                                 1D 80/20 AA/AMPS 5000 87,100 48.6                                              4C 100% AA (COM) 0 3,730  9.2                                                  2C 100% AA 1000 65,600 46.8                                                  SET 2 - 70° C., 1 PPM POLYMER DOSAGE                                    4C   100% AA (COM) 0     3,730   39.8                                            2A 100% AA 500 -- 52.7                                                         2F 100% AA 5000 11,000 52.7                                                  SET 3 - 70° C.                                                          SAMPLE                                                                              POLYMER       PPM MBA                                                                              MW      DOSE    % INHIBITION                          __________________________________________________________________________       1G 80/20 AA/AMPS 0 7400 1 PPM 35.9                                             1I 80/20 AA/AMPS 5000 6400 1 PPM 56.8                                          1G 80/20 AA/AMPS 0 7400 4 PPM 63.0                                             1I 80/20 AA/AMPS 5000 6400 4 PPM 80.7                                          4B COM. AA/AMPS 0 8100 4 PPM 64.9                                            SET 4 - 80° C., 2.5 PPM POLYMER DOSAGE                                  SAMPLE                                                                              POLYMER       PPM MBA                                                                              MW      % INHIBITION                                  __________________________________________________________________________       1G 80/20 AA/AMPS 0 7,400 44.9                                                  1I 80/20 AA/AMPS 5000 6,400 57.6                                               4B COM. AA/AMPS 0 8,100 29.7                                                 SET 5 - 70° C., 1 PPM POLYMER DOSAGE                                    SAMPLE                                                                              POLYMER       PPM MBA                                                                              % INHIBITION                                          __________________________________________________________________________       1G 80/20 AA/AMPS 0 61.1                                                        1I 80/20 AA/AMPS 5000 77.9                                                     4B COM. AA/AMPS 0 58.9                                                         3A 60/20/20 AA/AMPS/DADMAC 0 53.3                                              3B 60/20/20 AA/AMPS/DADMAC 5000 62.2                                           3C 70/20/10 AA/AMPS/NVP 0 61.1                                                 3D 70/20/10 AA/AMPS/NVP 5000 68.9                                              1G 80/20 AA/AMPS 0 47.4                                                        1I 80/20 AA/AMPS 5000 61.9                                                     4B COM. AA/AMPS 0 43.3                                                         3E 80/20 AA/SAHS 0 34.0                                                        3F 80/20 AA/SAHS 5000 45.4                                                     3G 70/20/10 AA/AMPS/AM 0 42.3                                                  3H 70/20/10 AA/AMPS/AM 5000 55.7                                               31 80/20 AA/AM 0 26.8                                                          3J 80/20 AA/AM 5000 35.1                                                       3K 70/20/10 AA/AMPS/MA 0 32.0                                                  3L 80/20/10 AA/AMPS/MA 5000 41.2                                               3M 80/20 AA/MA 0 24.7                                                          3N 80/20 AA/MA 5000 33.0                                                       3O 100% AMPS 0 18.6                                                            3P 100% AMPS 5000 25.8                                                         3Q 70/20/10 AA/AMPS/TBAM 0 39.1                                                3R 70/20/10 AA/AMPS/TBAM 5000 47.8                                             3S HOMOPOLYMER MAn 0 22.8                                                      3T HOMOPOLYMER MAn 5000 31.5                                                 __________________________________________________________________________

Calcium Carbonate Inhibition Test Procedure

All tests for calcium carbonate inhibition were conducted according to the following procedure:

1. Add 50 ml 0.023 M calcium stock solution (prepared from CaCl₂ and neutralized to pH 8.5) to glass vessel.

2. Add 0 (control), 0.1, 0.25 or 0.5 ml of 1 g/l active polymer solution (neutralized to pH 8) 1, 2.5 and 5 ppm respectively, to vessel.

3. Add 50 ml 0.023 M carbonate stock solution (prepared from Na₂ CO₃ and neutralized to pH 8.5) to vessel.

4. Cap vessel and shake to mix.

5. Place jars in forced air oven set at required temperature (70 or 80° C.) for 17 hrs. After approximately 60 minutes, loosen cap and recap to release pressure.

6. After 17 hrs., remove from oven and let cool to room temperature.

7. Filter through 0.45 micron filter.

8. Add 25 ml of filtered solution to beaker with 25 ml of water.

9. Add 3 ml of water hardness buffer solution and calcium indicator.

10. Titrate with 0.01 M EDTA solution. ##EQU1## where titration control=50 ml calcium stock solution+50 ml water prepared fresh prior to titration; EDTA (control)=0 ppm polymer

Example 5 Calcium Phosphate Inhibition 10 ppm Polymer, pH 9.5, 70° C.

    ______________________________________                                         SAMPLE POLYMER     PPM MBA   MW    % INHIBITION                                ______________________________________                                         1G     80/20 AA/AMPS                                                                              0         7,400 81.0                                          1H 80/20 AA/AMPS 1000 4,940 90.1                                               1I 80/20 AA/AMPS 5000 6,400 95.0                                               1D 80/20 AA/AMPS 5000 87,100 94.6                                              4B COM. AA/AMPS 0 8,100 81.3                                                 ______________________________________                                    

Calcium Phosphate Inhibition Test Procedure

All tests for calcium phosphate inhibition were conducted according to the following procedure:

1. Add 50 ml of 12 ppm PO₄ stock solution to glass vessel.

2. Add desired polymer dose (1, 5, or 10 ppm) to vessel.

3. Add 50 ml 500 ppm calcium stock solution containing 5 ppm Fe⁺².

4. Adjust samples to desired pH (9.5)

5. Cap and place in 70° C. forced air oven for 17 hrs.

6. After approximately 60 minutes, release pressure in vessels.

7. Remove from oven and filter immediately through 0.22 micron filter.

8. Analyze for PO₄ by ascorbic acid method. ##EQU2##

Example 6 Calcium Sulfate Inhibition pH 8.5, 70° C., 72 hrs

    ______________________________________                                         SAM-                                    % INHI-                                  PLE POLYMER PPM MBA MW DOSE BITION                                           ______________________________________                                         4C    100% AA (COM)                                                                              0         3730  .1 PPM                                                                               0                                        2G 100% AA 5000 11,000 .1 PPM 8.2                                              2A 100% AA 500  .1 PPM 8.2                                                     4B COM. AA/AMPS 0 8100 .1 PPM 5.5                                              1I 80/20 AA/AMPS 5000 6400 .1 PPM 10.9                                         4B COM. AA/AMPS 0 8100 .5 PPM 24.7                                             1G 80/20 AA/AMPS 0 7400 .5 PPM 28.7                                            1I 80/20 AA/AMPS 5000 6400 .5 PPM 35.6                                       ______________________________________                                    

Calcium Sulfate Test Procedure

All tests for calcium sulfate inhibition were conducted according to the following procedure:

1. Add 50 ml 15.3 g/l solution of calcium chloride (pH 8.5) to glass vessel.

2. Add desired polymer dose (0.1 or 0.5 ppm) to vessel.

3. Add 50 ml 8.1 g/l sodium sulfate solution (pH 8.5) to vessel.

4. Place in 70° C. forced air oven for 72 hrs. Release pressure after 1 hr.

5. Cool to room temperature

6. Filter through 0.22 micron filter

7. Titrate for calcium with EDTA. ##EQU3## where titration control=50 ml calcium stock solution+50 ml water prepared fresh prior to titration; EDTA (control)=0 ppm polymer

Example 7 Iron Oxide Dispersion

    __________________________________________________________________________     SET 1                                                                          SAMPLE                                                                               POLYMER DOSAGE                                                                              PPM MBA                                                                              % T 1 hr                                                                            % T 2 hr                                                                            % T 3 hr                                    __________________________________________________________________________       CONTROL NONE 0  43.7 54.2 67.0                                                 1E 60/20 AA/AMPS 10 PPM 0 41.4 43.8 49.2                                       1F 80/20 AA/AMPS 10 PPM 1000 34.3 36.9 40.2                                  SET 2                                                                          SAMPLE                                                                               POLYMER DOSAGE                                                                              PPM MBA                                                                              % T 1 hr                                              __________________________________________________________________________       CONTROL NONE 0  59.4                                                           1C 80/20 AA/AMPS 0 0 38.1                                                      1D 80/20 AA/AMPS 1 PPM 5000 34.3                                               4A COM. AA/AMPS 1 PPM 0 42.4                                                 SET 3                                                                          CONTROL                                                                              NONE    0          59.4                                                    4C COM. AA 10 PPM 0 52.0                                                       2B AA 10 PPM 1000 43.4                                                         2C AA 10 PPM 1000 46.8                                                       __________________________________________________________________________

Iron Oxide Inhibition Test Procedure

All tests for iron oxide inhibition were conducted according to the following procedure:

1. Prepare 200 ppm suspension of iron oxide in the presence of 250 ppm calcium.

2. Mix for 30 minutes.

3. Place 100 ml aliquots into glass vessels.

4. Add polymer at desired concentration.

5. Agitate samples for 15 minutes.

6. Let stand for desired time period.

7. Pipet 10 ml aliquot from top and measure % transmittance with a spectrophotometer at 720 nm.

8. The lower the % transmittance, the greater dispersion capability.

Example 8

    ______________________________________                                         SAMPLE   POLYMER     DOSAGE   PPM MBA %T 2.5 hr                                ______________________________________                                         CONTROL  NONE        0                39.8                                       4C COM. AA 10 PPM 0 35.4                                                       2C AA 10 PPM 1000 31.5                                                         1C 80/20AA/AMPS 10 PPM 0 10.3                                                  1D 80/20AA/AMPS 10 PPM 5000 6.8                                                1F 80/20AA/AMPS 10 PPM 1000 7.7                                              ______________________________________                                    

Clay Dispersion Procedure

All tests for clay dispersion were conducted as in the iron oxide test procedure except that a 1000 ppm clay suspension was prepared in the presence of 250 ppm calcium.

Examples 4-8 demonstrate that the polymer compositions of this invention possess enhanced capability to inhibit scale formation, precipitation or deposition, and provide increased dispersion of insoluble particulates in process waters.

Example 9 Calcium Carbonate Viscosity Reduction--70% Slurry

Two structured sodium polyacrylate polymers were evaluated against a commercially available dispersant commonly used in this application, according to the following procedure:

1. Add the following to a 400 ml beaker:

a. 100 ml water,

b. 4.5 ml 10% active polymer solution, and

c. Add 250 g calcium carbonate slowly while mixing.

2. After all calcium carbonate is added, mix at high speed for 15 minutes.

3. Pour into an 8 oz jar.

4. Measure viscosity with Brookfield viscometer, Model RVF, at 20 rpm.

5. Add additional polymer in 4.5 ml increments, upon each addition repeat step 2 for 5 minutes then repeat step 4.

    ______________________________________                                         SAMPLE  PPM MBA   MW       DOSAGE VISCOSITY (CPS)                              ______________________________________                                         4C      0         3,730     4.5 ml                                                                               --                                                 9.0 ml 48,740                                                                 13.5 ml 6,620                                                                  18.0 ml 5,790                                                                  22.5 ml 5,950                                                               2D 1250 7,400  4.5 ml --                                                           9.0 ml 35,960                                                                 13.5 ml 2,980                                                                  18.0 ml 3,560                                                               2F 5000 11,000  4.5 ml --                                                          9.0 ml 42,350                                                                 13.5 ml 3,750                                                                  18.0 ml 4,230                                                             ______________________________________                                    

Example 10 Kaolin Clay Viscosity Reduction--70% Slurry

A series of 80/20 AA/AMPS copolymers were evaluated as dispersants for a 70% slurry of kaolin clay. The test procedure used was identical to the procedure of Example 9 except that, 10% active polymer and 10% active sodium carbonate were added in 10 ml increments. Performance was measured with a Brookfield viscometer, Model RVF, at 20 rpm.

    ______________________________________                                         SAMPLE  PPM MBA   MW       DOSAGE VISCOSITY (CPS)                              ______________________________________                                         1E      0         19,300   1.5 ml 1265                                              2.0 ml 860                                                                     2.5 ml 865                                                                  1F 1000 18,200 1.5 ml 925                                                         2.0 ml 750                                                                     2.5 ml 740                                                                ______________________________________                                    

Example 11 Kaolin Clay Viscosity Reduction--70% Slurry

    ______________________________________                                                                      VISCOSITY                                                                               VISCOSITY                                  SAM- PPM  DOSAGE (CPS) (DN-cm X10.sup.5)                                       PLE MBA MW (LB/TON) BROOKFIELD HERCULES                                      ______________________________________                                                                               Measured at                                     1100 rpm                                                                  4F 0 4,500 3.25 830                                                               3.50 484                                                                       3.75 283                                                                       4.00 270 7.2                                                                2D 1,250 7,400 2.75 768                                                           3.00 350                                                                       3.25 297                                                                       3.50 340 4.8                                                                2F 5,000 11,000 2.75 430                                                          3.00 470 5.9                                                                     Measured at                                                                    4400 rpm                                                                  4F 0 4,500 3.00 752                                                               3.25 163 42.0                                                               2K 15,000 -- 3.00 1057                                                            3.25 255 28.0                                                             ______________________________________                                    

The above tests were conducted using hydrated mid-Georgia kaolin clay.

Example 12 Kaolin Clay Viscosity Reduction--70% Slurry

    ______________________________________                                                                      VISCOSITY                                                                               VISCOSITY                                  SAM- PPM  DOSAGE (CPS) (DN-cm X10.sup.5)                                       PLE MBA MW (LB/TON) BROOKFIELD HERCULES                                      ______________________________________                                                                               Measured at                                     4400 rpm                                                                  4F 0 4,500 2.5 250 3.8                                                         2D 1250 7400 2.5 320 2.7                                                       2L 5000 -- 3.0 250 2.8                                                         2M 5000 -- 3.0 360 3.2                                                       ______________________________________                                    

The above example was conducted using Eastern Georgia clay, which generally is finer in particle size than mid-Georgia kaolin clay.

Example 13 Calcined Kaolin Viscosity Reduction--50% Slurry

    ______________________________________                                         CALCINED KAOLIN VISCOSITY REDUCTION - 50% SLURRY                                                                       MAX. RPM                                     VISCOSITY ACHIEVED                                                          PPM  DOSAGE HERCULES at 16                                                    SAMPLE MBA MW LB./TON (Cps) dyne-cm X10.sup.5                                ______________________________________                                         4F     0       4500    2.0    784     780                                           2.5 779 785                                                                 2D 1250 7400 2.0 679 900                                                          2.5 611 1000                                                                2K 15,000  2.0 799 765                                                            2.5 593 1030                                                              ______________________________________                                    

The Hercules viscosity data shown in Example 13 give both a Hercules viscosity number in dynes and an rpm reading. The procedures for evaluating both hydrated and calcined kaolin slurries are given below:

The 70% hydrated kaolin slurry used in Examples 11-13 were prepared as follows:

1. Prepare solutions of 10% active polymer and 10% active sodium carbonate.

2. Weigh out 500 g clay.

3. Weigh 200 g water into vessel for high speed mixer.

4. Add 2 pounds/ton active sodium carbonate.

5. Add 2 pounds/ton active polymer.

6. Mix until homogeneous and then add clay to vessel while mixing at as high a speed as possible.

7. If mixture is not fluid, add additional polymer and sodium carbonate at equal concentrations. Mix for 1 minute at high speed.

8. After all clay is added check pH of slurry (should be between 6.5-7.5).

9. Check % solids (should be approximately 70.2%)

10. Check Brookfield viscosity with Model RVF spindle 1 or 2 at 20 rpm.

11. Record viscosity--Add additional 0.25 pounds/ton until optimum is reached (add 0.25 pounds/ton of sodium carbonate along with polymer).

12. Take Hercules viscosity on final sample at either 1100 or 4400 rpm, using B Bob.

The 50% calcined kaolin slurry used in Example 14 was prepared as follows:

1. Weigh out 300 g calcined kaolin.

2. Weigh 288.5 g water into vessel for low sheer mixer.

3. Add 1.5 g each of 10% active dispersant solution and 10% active sodium carbonate solution.

4. Mix until homogeneous.

5. Add clay to water mixture slowly.

6. After all clay is added, mix at high speed for 1 minute.

7. Measure pH and % solids (pH should be 6.5-7.5 and % solids should be approximately 50%).

8. Take Hercules viscosity at 1100 rpm, using B Bob.

Examples 9-13, described above, demonstrate that the polymer compositions of this invention possess enhanced capability to reduce the viscosity of mineral slurries compared to existing technology.

While described herein are a number of embodiments of this invention, it is apparent that the basic constructions may be altered to provide other embodiments which utilize the products of this invention. Therefore, it will be appreciated that the scope of this invention is to be defined by the appended claims, rather than by the specific embodiments which have been presented by way of example. 

I claim:
 1. A dispersant polymer composition having a molecular weight of less than about 50,000 comprising:at least one unsaturated organic monomer or salts thereof, wherein each unsaturated organic monomer is independently selected from the group consisting of monoethylenically unsaturated carboxylic acids, monoethylenically unsaturated carboxylic acid anhydrides, monoethylenically unsaturated sulfonic acids, and sulfonated styrene; and at least one structure-inducing agent.
 2. The dispersant polymer composition according to claim 1, wherein each unsaturated organic monomer is independently selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, maleic anhydride, 2-acrylamido-2-methylpropane sulfonic acid, 2-methacrylamido-2-methylpropane sulfonic acid, and allyloxy-2-hydroxypropyl sulfonic acid.
 3. The dispersant polymer composition according to claim 1, wherein the structure-inducing agent is a crosslinking or branching agent.
 4. The dispersant polymer composition according to claim 3, wherein the structure-inducing agent is independently selected from the group consisting of polyunsaturated acrylic amides, polyunsaturated acrylic esters, alkenyl-substituted heterocycles, triallylic or tetraallylic quaternary ammonium halides, and aldehydes.
 5. The dispersant polymer composition according to claim 4, wherein the structure-inducing agent is independently selected from the group consisting of methylenebisacrylamide, triallylmethylammonium chloride, ethylene glycol diacrylate, glyoxal and formaldehyde.
 6. The dispersant polymer composition according to claim 1, wherein the concentration of structure-inducing agent is between about 50 and about 20,000 ppm. 